The present invention relates generally to the art of railway car doors. More particularly, the invention pertains to a greaseless hanger assembly for plug-type railway car doors, and will be described with particular reference thereto. However, it is to be appreciated that the invention is also applicable to other related environments where a hanger assembly and crank are employed in conjunction with a rotating member or shaft.
Typical plug-type railway car doors are mounted on the side of a railway car and include a series of panels or sheeting reinforced by horizontally disposed channels at the top, bottom and intermediate portions of the door. A pair of vertically oriented elongated support members such as pipes, rods or bars are configured to support the door on the railway car itself. The elongated support members are typically provided with upper and lower cranks attached to the ends thereof which serve as lever arms for laterally moving the door into and out of an opening defined in the car. Upon actuation of a driving mechanism, such as a manually operated gear assembly, the support members are rotated causing corresponding rotation of the upper and lower cranks. Rotation of the cranks, in turn, draws the door laterally from the door opening until the door is supported on a track disposed adjacent a side of the car. The door is moveably supported on the track by roller hangers which enable the door to slide longitudinally along the side of the car.
More particularly, the lower cranks connect the elongated support members to each respective roller hanger assembly. The lower cranks include a crank end in the form of a pin portion secured to the bottom of the corresponding support member, a crank arm, and a crank pin. Typically, the crank pin is rotatably mounted to the roller hanger assembly. The portion of the roller hanger assembly that receives the crank pin includes a fitting surrounding the crank pin for retaining a lubricant. Grease is commonly used as the lubricant for providing substantially friction-free rotation of the crank pin within the roller hanger assembly. Grease, however, has several disadvantages.
First, grease is difficult to maintain and seal, often leaking or escaping from its intended working environment. Thus, grease filled hanger assemblies must be continuously monitored to ensure the continued presence of lubricant. Second, grease degrades over time, especially when exposed to harsh environments such as those experienced by railway cars and, thus, must be periodically replaced. Ensuring periodic maintenance is quite cumbersome because there is no easy and convenient place for servicing railway cars and there is no simple tracking method for determining when such maintenance should be implemented. Typically, railway cars remain on the tracks for extended periods of time at diverse locations, thereby making is difficult to maintain any regular maintenance schedule. Third, it is relatively expensive to maintain grease filled hanger assemblies, especially when the cost is calculated over the life of the railway car.
Accordingly, it has been considered desirable to develop a crank and hanger assembly for plug-type railway car doors that addresses the foregoing difficulties and others while providing better and more advantageous overall results.
In accordance with one aspect of the invention, a railway car door assembly includes a substantially planar door member and a pair of elongated support members which are rotatably mounted to the door member. An associated drive mechanism is employed to selectively impart a rotational force to the support members for shifting the door between fully closed and cracked positions. A pair of greaseless crank and roller hanger assemblies support the door on a track in the cracked position for movement therealong toward a fully opened position.
In accordance with a more specific aspect of the invention, each of the greaseless crank and roller hanger assemblies includes a crank comprised of a crank arm secured at one end to the corresponding elongated support member and a crank pin cooperatively connected thereto at the other end. The crank pin includes an inner portion secured to the crank arm and an outer shaft portion. The shaft portion includes a peripherally recessed area extending along an axial segment thereof, and a self-lubricating sleeve closely embraces the recessed area.
According to yet a further aspect of the invention, the self-lubricating sleeve is comprised of a high-density polyethylene material.
In accordance with another aspect of the invention, the greaseless roller hanger assembly includes a housing having a channel or well for receiving the crank pin shaft portion and a roller mounted to the housing for rotational movement along the track.
According to still another aspect of the invention, the greaseless roller hanger assembly includes at least one self-lubricating washer disposed at the bottom wall of the channel or well. In one arrangement, multiple oil-impregnated washers, preferably of bronze or similar material, are used and are disposed in a stacked relationship to each other. In another arrangement, a single self-lubricating washer comprised of a high-density polyethylene material is used.
Another aspect of the invention contemplates a method for greaseless mounting of a crank assembly for selective rotation relative to a roller hanger assembly. The method comprises the steps of substantially surrounding a portion of a crank pin with a polyethylene sleeve and positioning a polyethylene washer at the bottom wall of a channel or well within the roller hanger assembly. The crank pin is positioned in cooperating relation with the channel such that a bottom face of the crank pin is in contacting relation with the polyethylene washer and a portion of the polyethylene sleeve is in contacting relation with the inner wall or surface of the channel.
A principal advantage of the present invention resides in the provision of a crank and roller hanger assembly which operates effectively without the need for or use of a separate lubricant.
Another advantage of the invention is found in the provision of a crank and roller hanger assembly that is easy to maintain.
Still another advantage of the invention resides in the provision of a crank and roller hanger assembly that is relatively cost effective.
Still other benefits and advantages of the invention will become apparent to those skilled in the art upon a reading and understanding of the detailed specification.